using System;
using Microsoft.UI.Input;
using Windows.System;

namespace LayersShell;

/// Maps WinUI virtual keys to the `layers_key_event` named-code + text protocol.
///   named: 0=Character, 1=Enter, 2=Escape, 3=Backspace, 4=Tab,
///          5=ArrowLeft, 6=ArrowRight, 7=ArrowUp, 8=ArrowDown,
///          9=Delete, 10=Home, 11=End.
///   mods:  1=Shift, 2=Ctrl, 4=Alt, 8=Logo (Win).
internal static class WinKeyMap
{
    public static uint MapVirtualKey(VirtualKey key) => key switch
    {
        VirtualKey.Enter      => 1,
        VirtualKey.Escape     => 2,
        VirtualKey.Back       => 3,
        VirtualKey.Tab        => 4,
        VirtualKey.Left       => 5,
        VirtualKey.Right      => 6,
        VirtualKey.Up         => 7,
        VirtualKey.Down       => 8,
        VirtualKey.Delete     => 9,
        VirtualKey.Home       => 10,
        VirtualKey.End        => 11,
        _                     => 0,
    };

    public static string? TextForKey(VirtualKey key)
    {
        // Letters + digits + punctuation produced by the shell directly. Shift/altgr composition
        // is left to the iced layer's text_input which re-evaluates the character path.
        if (key >= VirtualKey.A && key <= VirtualKey.Z)
        {
            char c = (char)('a' + (int)(key - VirtualKey.A));
            return c.ToString();
        }
        if (key >= VirtualKey.Number0 && key <= VirtualKey.Number9)
        {
            char c = (char)('0' + (int)(key - VirtualKey.Number0));
            return c.ToString();
        }
        return key switch
        {
            VirtualKey.Space => " ",
            _ => null,
        };
    }

    public static uint CurrentModifiers()
    {
        uint m = 0;
        if ((InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Shift)   & Windows.UI.Core.CoreVirtualKeyStates.Down) == Windows.UI.Core.CoreVirtualKeyStates.Down) m |= 1;
        if ((InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Control) & Windows.UI.Core.CoreVirtualKeyStates.Down) == Windows.UI.Core.CoreVirtualKeyStates.Down) m |= 2;
        if ((InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.Menu)    & Windows.UI.Core.CoreVirtualKeyStates.Down) == Windows.UI.Core.CoreVirtualKeyStates.Down) m |= 4;
        if ((InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.LeftWindows)  & Windows.UI.Core.CoreVirtualKeyStates.Down) == Windows.UI.Core.CoreVirtualKeyStates.Down) m |= 8;
        if ((InputKeyboardSource.GetKeyStateForCurrentThread(VirtualKey.RightWindows) & Windows.UI.Core.CoreVirtualKeyStates.Down) == Windows.UI.Core.CoreVirtualKeyStates.Down) m |= 8;
        return m;
    }
}